Spherical mounted cylindrical roller bearing system

ABSTRACT

A bearing system is provided in one example embodiment and may include an inner bearing assembly comprising a spherical bearing and an outer race; an outer bearing assembly comprising a plurality of cylindrical roller bearings, an inner race, and an outer race; and a race element comprising an inner surface and an outer surface, wherein the outer surface of the race element is the inner race for the outer bearing assembly and the inner surface of the race element is associated with the outer race for the inner bearing assembly. The inner bearing assembly allows tilting movements of the bearing system and the outer bearing assembly allows rotational movements and supports, at least in part, radial loads for the bearing system.

TECHNICAL FIELD

This disclosure relates in general to the field of aircraft and, moreparticularly, though not exclusively, to a spherical mounted cylindricalroller bearing system.

BACKGROUND

There are numerous considerations involved in the design of tiltrotoraircraft and other aircraft, including size, weight, power efficiency,fuel efficiency, noise, vibration, structural loads, and so forth. Inmany cases, however, it may be challenging to improve certain aspects ofan aircraft without disrupting other aspects. For example, bearingdesign for an aircraft propulsion system can implicate numerousperformance considerations and is often an extremely challenging aspectof aircraft design.

SUMMARY

According to one aspect of the present disclosure, a bearing system maybe provided and may include an inner bearing assembly comprising aspherical bearing and an outer race; an outer bearing assemblycomprising a plurality of cylindrical roller bearings, an inner race,and an outer race; and a race element comprising an inner surface and anouter surface, wherein the outer surface of the race element is theinner race for the outer bearing assembly and the inner surface of therace element is associated with the outer race for the inner bearingassembly. The inner bearing assembly allows tilting movements of thebearing system and the outer bearing assembly allows rotationalmovements and supports, at least in part, radial loads for the bearingsystem. In some cases, the outer race of the inner bearing assembly canbe integral with the race element. The outer race for the outer bearingassembly can be rim material of a gear.

In some cases, the race element may further include inner securingelements associated with the inner surface of the race element thatsecure the outer race of the inner bearing assembly to the sphericalbearing; an outer shoulder associated with the outer surface of the raceelement that maintains alignment of the plurality of cylindrical rollerbearings with the inner race of the outer bearing assembly; and an outerstructural element associated with the outer surface of the race elementthat is to receive a retaining device. The retaining device can securethe plurality of cylindrical roller bearings to the inner race of theouter bearing assembly and the inner race of the outer bearing assemblymay provide a clearance distance that allows axial movements of theplurality of cylindrical roller bearings along the inner race. Thespherical bearing may have an inner diameter to facilitate mounting thebearing system on a post.

According to another aspect of the present disclosure, a planetary gearsystem may be provided and may include a planet gear further comprisinga bearing system in which the bearing system may further include aninner bearing assembly comprising a spherical bearing and an outer race;an outer bearing assembly comprising a plurality of cylindrical rollerbearings, an inner race, and an outer race; and a race elementcomprising an inner surface and an outer surface, wherein the outersurface of the race element is the inner race for the outer bearingassembly and the inner surface of the race element is associated withthe outer race for the inner bearing assembly. The planetary gear systemmay further include a sun gear, a ring gear, and a carrier that includesa plurality of carrier posts, wherein the planet gear is one of aplurality planet gears of the planetary gear system and each planet gearis mounted to each carrier post of the plurality of carrier posts.

According to another aspect of the present disclosure, an aircraft maybe provided and may include a fuselage; and at least one propulsionsystem in which the at least one propulsion system includes at least oneplanetary gear system and the at least one planetary gear system mayfurther include a plurality of planet gears, wherein each planet gearfurther comprises a bearing system and the bearing system of each planetgear may further include an inner bearing assembly comprising aspherical bearing and an outer race; an outer bearing assemblycomprising a plurality of cylindrical roller bearings, an inner race,and an outer race; and a race element comprising an inner surface and anouter surface, wherein the outer surface of the race element is theinner race for the outer bearing assembly and the inner surface of therace element is associated with the outer race for the inner bearingassembly. In some cases, the aircraft may be a tiltrotor aircraftcomprising at least two propulsion systems having proprotors that aremoveable between a helicopter mode and an airplane mode. In some cases,the aircraft may be a rotorcraft.

BRIEF DESCRIPTION OF THE DRAWINGS

To provide a more complete understanding of the present disclosure andfeatures and advantages thereof, reference is made to the followingdescription, taken in conjunction with the accompanying figures, inwhich like reference numerals represent like elements.

FIGS. 1A-1B and 2 are simplified schematic diagrams of example aircraft,in accordance with certain embodiments.

FIGS. 3A-3B are simplified diagrams illustrating example detailsassociated with an example planetary gear system, in accordance withcertain embodiments.

FIGS. 4A-4B are simplified diagrams illustrating example detailsassociated with an example bearing system of an example planet gear, inaccordance with certain embodiments.

FIG. 5 is a simplified exploded view diagram illustrating yet otherexample details associated with the bearing system of FIGS. 4A-4B, inaccordance with certain embodiments.

FIG. 6 is a simplified side, cross-sectional view diagram illustratingexample details associated with an example race element, in accordancewith certain embodiments.

DETAILED DESCRIPTION

The following disclosure describes various illustrative embodiments andexamples for implementing the features and functionality of the presentdisclosure. While particular components, arrangements, and/or featuresare described below in connection with various example embodiments,these are merely examples used to simplify the present disclosure andare not intended to be limiting. It will of course be appreciated thatin the development of any actual embodiment, numerousimplementation-specific decisions must be made to achieve thedeveloper's specific goals, including compliance with system, business,and/or legal constraints, which may vary from one implementation toanother. Moreover, it will be appreciated that, while such a developmenteffort might be complex and time-consuming; it would nevertheless be aroutine undertaking for those of ordinary skill in the art having thebenefit of this disclosure.

In the Specification, reference may be made to the spatial relationshipsbetween various components and to the spatial orientation of variousaspects of components as depicted in the attached drawings. However, aswill be recognized by those skilled in the art after a complete readingof the present disclosure, the devices, components, members,apparatuses, etc. described herein may be positioned in any desiredorientation. Thus, the use of terms such as ‘above’, ‘below’, ‘upper’,‘lower’, ‘top’, ‘bottom’, or other similar terms to describe a spatialrelationship between various components or to describe the spatialorientation of aspects of such components, should be understood todescribe a relative relationship between the components or a spatialorientation of aspects of such components, respectively, as thecomponents described herein may be oriented in any desired direction.When used to describe a range of dimensions or other characteristics(e.g., time, pressure, temperature) of an element, operations, and/orconditions, the phrase ‘between X and Y’ represents a range thatincludes X and Y.

Additionally, as referred to herein in this Specification, the terms‘forward’, ‘aft’, ‘inboard’, and ‘outboard’ may be used to describerelative relationship(s) between components and/or spatial orientationof aspect(s) of a component or components. The term ‘forward’ may referto a special direction that is closer to a front of an aircraft relativeto another component or component aspect(s). The term ‘aft’ may refer toa special direction that is closer to a rear of an aircraft relative toanother component or component aspect(s). The term ‘inboard’ may referto a location of a component that is within the fuselage of an aircraftand/or a spatial direction that is closer to or along a centerline ofthe aircraft relative to another component or component aspect, whereinthe centerline runs in a between the front and the rear of the aircraft.The term ‘outboard’ may refer to a location of a component that isoutside the fuselage of an aircraft and/or a special direction thatfarther from the centerline of the aircraft relative to anothercomponent or component aspect.

Further, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed. Exampleembodiments that may be used to implement the features and functionalityof this disclosure will now be described with more particular referenceto the accompanying FIGURES.

Referring to FIGS. 1A-1B, FIGS. 1A-1B illustrate perspective views of anexample aircraft, which in this example is a tiltrotor aircraft 100.Tiltrotor aircraft 100 includes a fuselage 102, a landing gear 104, awing 106, a tail member 108, a propulsion system 110, and a propulsionsystem 112. The fuselage 102 is the main body of the tiltrotor aircraft100, which may include a cabin (e.g., for crew, passengers, and/orcargo) and/or may house certain mechanical and electrical components fortiltrotor aircraft 100. In the illustrated embodiment, tail member 108may be used as a vertical stabilizer.

Propulsion system 110 includes a proprotor 120 that includes a pluralityof rotor blades 122. Propulsion system 112 includes a proprotor 130 thatincludes a plurality of rotor blades 132. Various engine(s),gearbox(es), and drive shaft(s) may be provided in variousconfigurations to provide torque to proprotors 120 and 130. For example,in at least one embodiment, propulsion system 110 may include an engine124 within a nacelle 128 that is mechanically connected to a proprotorgearbox 126 to provide torque to proprotor 120 and propulsion system 112may include an engine 134 within a nacelle 138 that is mechanicallyconnected to a proprotor gearbox 136 to provide torque to proprotor 130to provide flight capabilities (e.g., flight direction, thrust, and/orlift) for tiltrotor aircraft 100. The position or proprotors 120 and130, as well as the pitch of rotor blades 122 and 132, can beselectively controlled in order to selectively control direction,thrust, and/or lift of tiltrotor aircraft 100.

The position of proprotors 120 and 130 are moveable between a helicoptermode and an airplane mode to provide different types of thrust fortiltrotor aircraft 100. FIG. 1A illustrates tiltrotor aircraft 100 inhelicopter mode in which proprotors 120 and 130 are positionedsubstantially vertical to provide a lifting thrust. FIG. 1B illustratestiltrotor aircraft 100 in an airplane mode in which proprotors 120 and130 are positioned substantially horizontal to provide a forward thrustin which a lifting force is supplied by wing 106. It should beappreciated that tiltrotor aircraft can be operated such that proprotors120 and 130 can be selectively positioned between airplane mode andhelicopter mode, which can be referred to as a conversion mode.

Referring to FIG. 2, FIG. 2 illustrates a side view of an exampleaircraft, which in this example is a rotorcraft 200. Rotorcraft 200includes a propulsion system 210, a fuselage 202, landing gear 204, atail rotor or anti-torque system 206, an empennage 208, and a tailstructure 212. Propulsion system 210 may include one or more enginesthat is/are mechanically connected to a main rotor gearbox 214 toprovide torque to a rotor system 216 that includes rotor blades 218 andalso to provide torque to anti-torque system 206. The pitch of eachrotor blade 218 can be managed or adjusted in order to selectivelycontrol direction, thrust, and lift of rotorcraft 200. The fuselage 202is the main body of the rotorcraft, which may include a cabin (e.g., forcrew, passengers, and/or cargo) and/or may house certain mechanical andelectrical components (e.g., engine(s), transmission, and/or flightcontrols). In the illustrated embodiment, tail structure 212 may be usedas a horizontal stabilizer.

Propulsion systems for aircraft, such as tiltrotor aircraft 100 and/orrotorcraft 200, can include epicyclic gear systems, such as planetarygear systems. In general, a planetary gear system for a tiltrotoraircraft, rotorcraft, etc. is a high power density gear reduction systemthat provides for the ability to reduce the speed of input rotations tothe gear system while increasing the torque of output rotations from thegear system.

Referring to FIGS. 3A-3B, FIGS. 3A-3B are simplified schematic diagramsillustrating example details associated with an example planetary gearsystem 300, in accordance with certain embodiments. In at least oneembodiment the planetary gear system 300 may include a sun gear 302, sixplanet gears 304 (sometimes referred to as pinions), a ring gear 306,and a carrier 308. Each planet gear 304 may include a spherical mountedcylindrical roller bearing system 312. Each planet gear 304 can bemounted to a carrier post 310 of carrier 308 via its bearing system 312.Although planetary gear system 300 is illustrated with six planet gears304, the number of planet gears shown in planetary gear system 300 isprovided for illustrative purposes only. It is to be understood that aplanetary gear system may include any number of planet gears inaccordance with embodiments described herein.

In some embodiments, carrier 308 may be mechanically coupled to a mast(not shown) of a propulsion system for an aircraft; however, in otherembodiments, carrier 308 may be mechanically coupled to another gearsystem of a propulsion system for the aircraft, in which the carrier mayprovide an input torque to the other gear system.

Although the planetary gear system 300 can be operated in multiple waysby restricting rotational motion of any one of sun gear 302, ring gear306, or carrier 308, one potential method for operating planetary gearsystem 300 may include allowing rotation of sun gear 302 and carrier 308about a central axis (generally indicated as dashed-line 314) of a shaft316 to which the sun gear 302 is mounted. In at least one embodiment,for example, with the ring gear 306 prevented from rotating about thecentral axis 314, a clockwise rotation (generally indicated by arrow318) of the shaft 316 and associated sun gear 302 results in acounter-clockwise rotation (generally indicated by arrow 319) of eachplanet gear 304 and a clockwise rotation of the carrier 308. In thisembodiment, each of the sun gear 302, the ring gear 306, and the planetgears 304 are formed as involute gears so that, when functioning undernormal operating conditions and without failure of any of the gears,contact between two gear teeth occurs along a single line of action (orpressure line of contact).

While a single line of action is desirable between gear teeth of gearsof a planetary gear system, changes in operating conditions, such asincreases or decreases in torque supplied to the sun gear of a planetarygear system of a propulsion system gearbox (e.g., a proprotor gearbox, amain rotor gearbox, or any other gearbox) can introduce the potentialfor misalignments between the gears. Such misalignments can cause loadsto be disproportionately focused on a particular portion of teeth and/orbearing systems for the gears, which can cause increased wear and/orpotential failure of teeth, gears, and/or bearing systems for aplanetary gear system of a gearbox, thus causing overall gearboxfailure.

One potential solution to account for potential misalignments betweengears may include increasing the stiffness of the carrier and itscarrier posts, which can limit potential misalignments. However,increasing the stiffness of the carrier increases its weight, which canimpact performance of the planetary gear system and the aircraft.Another potential solution to account for potential misalignmentsbetween gears may include using spherical roller bearings within thebearing system for each planet gear of the planetary gear system. For abearing system that includes spherical roller bearing, the bearings canrotate between a spherical-shaped inner race and a spherical-shapedouter race. As misalignments are introduced to the planetary gearsystem, the track of the spherical roller bearings can shift between thespherical-shaped inner and outer races to accommodate the misalignments.

Although spherical roller bearings provide for the ability toaccommodate misalignments between gears of a planetary gear system,manufacturing complexity and cost of planetary gear systems that utilizespherical roller bearing systems are increased in comparison toplanetary gear systems that utilize more conventional cylindrical rollerbearings. For example, to form the spherical-shaped outer race forspherical roller bearings, rim material of planet gears is milled, whichis both difficult and time-consuming, and results in increasedmanufacturing costs. Milling is also needed to form the spherical-shapedinner race, which further increases manufacturing costs. In addition,removing rim material from planet gears to form the spherical-shapedouter race causes decreased strength in the inner portion of the rim ascompared to outer portions of the rim. More complex design criteria andmanufacturing tolerances are needed to account for the decreasedstrength, which further increases manufacturing costs. Moreover, becausespherical bearings are a sphere, during operation of a spherical rollerbearing assembly, a spherical line that is the elliptical point ofcontact of the spherical roller bearings is carved into the inner andouter races of the assembly. As the bearings and the races wear, spallsdevelop and the gearbox eventually fails.

Another potential solution to accommodate potential misalignments is todevelop pattern corrections for gear teeth of the gears of a planetarygear system. Pattern correction for gear teeth is typically designed toaccommodate corrections for a narrow range of misalignment/torque.However, propulsion systems for aircraft such as tiltrotor aircraft 100and rotorcraft 200 typically have a wide torque band that is to besupported during operation. Providing pattern correction for a widerange of misalignment/torque can increase design complexity ofgearboxes, which can also increase manufacturing costs.

The present disclosure describes various embodiments that provide aspherical mounted cylindrical roller bearing system that includes acombined spherical bearing assembly and cylindrical roller bearingassembly for each planet gear of a planetary gear system. The sphericalmounted cylindrical roller bearing system allows tilting movements ofthe bearing system, which may accommodate tilting movements of theplanet gear with respect to the carrier post of the carrier, while alsoallowing rotational movements of the planet gear about a central axis ofthe carrier post and the planet gear. As discussed in further detailherein, spherical mounted cylindrical roller bearing systems asdiscussed for various embodiments described herein may provide numerousadvantages over other potential solutions that attempt to account formisalignments in planetary gear systems.

Example embodiments associated with a spherical mounted cylindricalroller bearing system are described below with more particular referenceto the remaining FIGS. Although example embodiments discussed herein aredescribed with reference to tiltrotor aircraft 100 and rotorcraft 200,it should be appreciated that tiltrotor aircraft 100 of FIGS. 1A-1B androtorcraft 200 of FIG. 2 are merely illustrative of a variety ofaircraft in which spherical mounted cylindrical roller bearing systemsmay be used in accordance embodiments of the present disclosure. Otheraircraft in which spherical mounted cylindrical roller bearing systemsmay be used can include, for example, fixed wing airplanes, hybridaircraft, unmanned aircraft, gyrocopters, a variety of helicopterconfigurations, and drones, among other examples. Moreover, it should beappreciated that even though spherical mounted cylindrical rollerbearing systems may be used in aircraft, bearing systems as discussedfor various embodiments described herein may also be used in a varietyof industries including, but not limited to, aerospace, non-aircrafttransportation (e.g., boats, automobiles, busses, etc.), railwaytransportation, and/or any other industry.

Referring to FIGS. 4A-4B, FIGS. 4A-4B are simplified diagramsillustrating example details associated with a particular sphericalmounted cylindrical roller bearing system 312 for a particular planetgear 304 of planetary gear system 300, in accordance with certainembodiments. In particular, FIG. 4A is a simplified side,cross-sectional view diagram illustrating example details associatedwith the spherical mounted cylindrical roller bearing system 312 for theplanet gear 304 and FIG. 4B is a simplified side, cross-sectional viewdiagram illustrating example features of a portion of the sphericalmounted cylindrical roller bearing system 312, in accordance withcertain embodiments. The cross-section of FIG. 4A is cut along a ling asgenerally indicated by the lines labeled ‘4A’ in FIG. 3B.

In at least one embodiment, spherical mounted cylindrical roller bearingsystem 312 for planet gear 304 may include an inner bearing assembly320, may include a spherical bearing 322 (sometimes referred to as a‘wobble’ bearing) and an outer race 324, and an outer bearing assembly330, which may include multiple cylindrical roller bearings 332, aninner race 334, and an outer race 336. As referred to herein in thisSpecification, the terms ‘inner bearing assembly’, ‘inner sphericalbearing assembly’, ‘spherical bearing assembly’, and variations thereofmay be used interchangeably and the terms ‘outer bearing assembly’,‘outer cylindrical roller bearing assembly’, ‘cylindrical roller bearingassembly’, and variations thereof may be used interchangeably. Furtheras referred to herein in this Specification, a spherical mountedcylindrical roller bearing system (e.g., spherical mounted cylindricalroller bearing system 312) may be referred to more generally as a‘bearing system’.

Bearing system 312 may further include a race element 340 that is sharedbetween the inner bearing assembly 320 and the outer bearing assembly330. The race element may include an inner surface 342 a and an outersurface 342 b and may provide different functions in accordance withvarious embodiments. In one embodiment, the inner surface 342 a of raceelement 340 may support and secure the outer race 324 to the sphericalbearing 322 of the inner bearing assembly 320 via inner securingelements 348 a and 348 b that may be integrally formed for the innersurface 342 a of the race element 340 and the outer surface 342 b ofrace element 340 may provide the inner race 334 of the outer bearingassembly 330. In another embodiment, the outer race of the innerspherical bearing assembly may be formed integral to the race element340 (e.g., a separate, non-integral outer race 324 for the inner bearingassembly 320 may not be needed) and the outer surface 342 b of raceelement 340 may provide the inner race 334 of the outer bearing assembly330.

In various embodiments, inner securing elements 348 a and 348 b of raceelement may be retaining lips, rings, shoulders, or any other structuralelement that may facilitate securing outer race 324 to spherical bearing322 for inner bearing assembly 320.

Race element 340 may further include an outer shoulder 344 that may beintegrally formed for the outer surface 342 b. The outer shoulder 344may be a structural feature of race element 340 that may help tomaintain alignment of cylindrical roller bearings 332 with the innerrace 334 for the outer bearing assembly 330. Race element 340 mayfurther include an outer structural element 346 that is on a side ofrace element 340 opposite from outer shoulder 344. The outer structuralelement 346 may provide structural features for race element 340 uponwhich a bearing retaining device 356 for bearing system 312 may besecured (e.g., a shoulder and retaining features upon which bearingretaining device can be secured). In at least one embodiment, thebearing retaining device 356 may facilitate securing the outer bearingassembly 330 and gear 304 to the inner bearing assembly 320.

Spherical bearing 322 may have an inner diameter 326 that facilitatesmounting the spherical bearing 322 (and bearing system 312) to thecarrier post 310. Spherical bearing 322 for the inner bearing assembly320 may be mounted to the carrier post 310 using a post retaining device354 that is secured to the carrier post 310. In some embodiments, aninner spacer 350 and an outer spacer 352 may be provided on opposingsides of the spherical bearing 322 to facilitate suitable clearances fortilting movements (generally indicated by arrows 370) that may occurbetween the carrier post 310 and planet gear 304, which bearing system312 may accommodate during operation of planetary gear system 300.

Planet gear 304 includes a rim 307 and teeth 305. In general, the rim307 can be described as the material of which the planet gear 304 iscomposed that extends radially inward (e.g., towards the carrier post310) from the root circle (comprising a root diameter) of the planetgear 304 to a first distance 311 at which the rim 307 material mayprovide the outer race 336 of the outer bearing assembly 330. Anotherportion of the rim 307 may extend radially inward from the root circleto a second distance 313 and may provide a shoulder 309 that may help,at least in part (e.g., along with a bearing cage of the cylindricalroller bearings), to maintain alignment and separation between thecylindrical roller bearings 332 for the outer race 336. More generally,the rim 307 is the material of the planet gear 304 that carries theplanet gear teeth 305.

In various embodiments, post retaining device 354 and bearing retainingdevice 356 may be any device or combination of devices that may be usedto secure the inner bearing assembly 320 and the outer bearing assembly330 (and planet gear 304) to a corresponding structure (e.g., to thecarrier post 310 for the post retaining device 354 or to the raceelement 340 for the bearing retaining device 356) and may include, butnot be limited to, threaded rings, washers, spacers, tension clips orrings, lock clips or pins, combinations thereof, or the like. In variousembodiments, outer structural element 346 may include threads, notches,holes, grooves, combinations thereof, and/or any other structuralfeature that may facilitate securing the bearing retaining device 356 tothe race element 340.

Spherical bearing 322 may have a spherical diameter 380. Eachcylindrical roller bearing 332 may have a length 384 and a diameter 386.In at least one embodiment, a length 390 of the inner race 334 of theouter bearing assembly 330 that is provided by the outer surface 342 bof the race element 340 may be longer than the combined length ofcylindrical roller bearings 332 included in the outer bearing assembly330 plus a length 388 of the shoulder 309 of rim 307 in order to providea clearance distance 382 that allows axial movements or shifting(generally indicated by arrows 378) of the cylindrical roller bearings332 about the inner race 334, as may be needed during operation. It isto be understood that features and/or elements (e.g., races, bearings,race element 340, retaining devices, spacers, etc.) of spherical mountedcylindrical roller bearing systems 312 as discussed for variousembodiments described herein may have any suitable dimensions, which mayvary depending on applications and/or implementations (e.g., gearsizing, tooth for gears, carrier post sizing, torque loads and/orrotational speeds to be supported, bearing sizing, gear and/or carriermaterials used, number of planet gears, etc.).

The spherical mounted cylindrical roller bearing system 312 may combinefeatures provided by spherical bearing 322 with features provided bycylindrical roller bearings 332 to allow the bearing system 312 to bothtilt in relation to carrier post 310, which may accommodate tiltingmovements 370 of the planet gear with respect to the carrier post 310,and to also allow rotational movements (generally indicated by arrows372) of the planet gear 304 about a central axis (generally indicated bydashed-line 374) of the planet gear 304 and bearing system 312.

By accommodating tilting movements via the spherical bearing for eachbearing system 312 mounted to each carrier post, each bearing system 312for each planet gear 304 of planetary gear system 300 can advantageouslymaintain radial loading (generally indicated by arrows 376) on thecylindrical roller bearings (e.g., torque loads are reacted radiallythrough the diameter of the cylindrical roller bearings and into thecarrier), which allows numerous advantages to be realized over otherpotential solutions that attempt to accommodate misalignment inplanetary gear systems.

One advantage of embodiments described herein may include providing abearing system that can accommodate both tilting movements androtational movements for a planet gear that does not implicate thedesign complexities and manufacturing costs that are associated withspherical roller bearing designs. One other advantage of embodimentsdescribed herein may include providing a bearing system that does notimplicate the need for a stiff (and heavy) carrier for a planetary gearsystem, which can reduce manufacturing costs for a gearbox. One otheradvantage of embodiments described herein may include providing abearing system that does not implicate the design complexities andmanufacturing costs that are associated with providing patterncorrections for gear teeth.

Features and/or elements (e.g., races, bearings, race element 340,retaining devices, spacers, etc.) of spherical mounted cylindricalroller bearing systems 312 and planet gears 304 may be composed of anysuitable material(s) including, but not limited to, a plastic,reinforced plastic, metal (e.g., aluminum, steel, etc.) and/or metalalloy, rubber, synthetic materials, fiberglass, reinforced fiberglass,ceramic materials, composite materials (e.g. a carbon composite such asa carbon fiber reinforced polymer (CFRP)), combinations thereof, or thelike. In various embodiments, spherical mounted cylindrical rollerbearing systems 312 may be formed using any suitable techniqueincluding, but not limited to, metal fabrication and/or machiningtechniques, combinations thereof, or the like.

Further, it is to be understood that the arrangement and/orconfiguration of features and/or elements of spherical mountedcylindrical roller bearing systems 312 are provided for illustrativepurpose only and are not meant to limit the broad scope of the presentdisclosure. For example, a spherical mounted cylindrical roller bearingsystem may be adapted to be implemented for any other type of gear(other than a planet gear) and/or for any other type of gear system(other than a planetary gear system) in accordance with embodimentsdescribed herein. Other variations can be envisioned. Some of thefeatures and/or elements illustrated in FIGS. 4A-4B are included inother ones of the remaining FIGS.; however, the discussion of thesefeatures and/or elements may not be repeated when discussing theremaining FIGS. for sake of brevity and any of these elements may takeany of the forms disclosed herein.

Referring to FIG. 5, FIG. 5 is a simplified exploded view diagramillustrating yet other example details associated with the sphericalmounted cylindrical roller bearing systems 312 of planet gears 304 forplanetary gear system 300, in accordance with certain embodiments. In atleast one embodiment, a particular spherical mounted cylindrical rollerbearing system 312 can be mounted to a particular carrier post 310 byproviding inner spacer 350, which can be slid onto the carrier post 310adjacent to a structural feature (e.g., a shoulder) 315 of the carrierpost 310. As discussed herein for various embodiments described herein,inner bearing assembly 320 can include spherical bearing 322, raceelement 340 (also shared with the outer bearing assembly 330), andoptionally outer race 324 (if it is not integrally formed into raceelement 340). Outer bearing assembly 330 can include cylindrical rollerbearings 332, which may be housed in a bearing cage 333, planet gear304, and race element 340 (also shared with inner bearing assembly 320).

In at least one embodiment, the inner bearing assembly 320 and the outerbearing assembly 330 can be assembled and secured together as a packagedsystem using bearing retaining device 356 to form spherical mountedcylindrical roller bearing system 312 In such an embodiment, oncebearing system 312 is assembled, it can be mounted to carrier post 310,in which case the spherical bearing 322 can be slid over the carrierpost 310 adjacent to inner spacer 350, outer spacer 352 can be slid overthe carrier post 310, and the bearing system 312 can be secured to thecarrier post 310 using post retaining device 354.

Referring to FIG. 6, FIG. 6 is a simplified side, cross-sectional viewdiagram illustrating example details associated with an example raceelement 600 that may be used in a spherical mounted cylindrical rollerbearing system, in accordance with certain embodiments. As illustratedin the embodiment of FIG. 6, race element 600 may include similarfeatures to race element 340, shown at least in FIG. 4A, in that raceelement 600 may include an inner surface 602 a, an outer surface 602 b,an outer shoulder 604, and an outer structural element 606 upon which abearing retaining device can be secured. The outer surface 602 b canprovide an inner race 610 for an outer bearing assembly and an outer(spherical) race 608 for an inner bearing assembly can be formed for theinner surface 602 a of the race element 600. The outer race 608 can matewith a spherical bearing for the inner bearing assembly of a givenspherical mounted cylindrical roller bearing system, in accordance withembodiments described herein. In some embodiments, the outer race 608can be formed for the inner surface 602 a of the race element, bymilling or otherwise machining the race element 600 to include sphericalfeatures for the race; however, in some embodiments, the race element600 may be cast or otherwise molded as a single element that includesthe outer race 608 integrally formed therein.

It is to be understood that the example arrangements and/orconfigurations of various features and/or elements associated with aspherical mounted cylindrical roller bearing system discussed in FIGS.4A-4B, 5, and 6 are only a few of the many possible arrangements and/orconfigurations of features and/or elements that may be provided for suchbearing systems and are not meant to limit the broad scope of thepresent disclosure. Virtually any arrangement and/or configuration offeatures and/or elements may be provided for a spherical mountedcylindrical roller bearing system and, thus, are clearly within thescope of the present disclosure.

The diagrams in the FIGS. illustrate the architecture, functionality,methods, and/or operation of possible implementations of variousembodiments of the present disclosure. Although several embodiments havebeen illustrated and described in detail, numerous other changes,substitutions, variations, alterations, and/or modifications arepossible without departing from the spirit and scope of the presentdisclosure, as defined by the appended claims. The particularembodiments described herein are illustrative only, and may be modifiedand practiced in different but equivalent manners, as would be apparentto those of ordinary skill in the art having the benefit of theteachings herein. Those of ordinary skill in the art would appreciatethat the present disclosure may be readily used as a basis for designingor modifying other embodiments for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein. Forexample, certain embodiments may be implemented using more, less, and/orother components than those described herein. Moreover, in certainembodiments, some components may be implemented separately, consolidatedinto one or more integrated components, and/or omitted. Similarly,methods associated with certain embodiments may be implemented usingmore, less, and/or other steps than those described herein, and theirsteps may be performed in any suitable order.

Numerous other changes, substitutions, variations, alterations, andmodifications may be ascertained to one of ordinary skill in the art andit is intended that the present disclosure encompass all such changes,substitutions, variations, alterations, and modifications as fallingwithin the scope of the appended claims.

One or more advantages mentioned herein do not in any way suggest thatany one of the embodiments described herein necessarily provides all thedescribed advantages or that all the embodiments of the presentdisclosure necessarily provide any one of the described advantages. Notethat in this Specification, references to various features included in‘one embodiment’, ‘example embodiment’, ‘an embodiment’, ‘anotherembodiment’, ‘certain embodiments’, ‘some embodiments’, ‘variousembodiments’, ‘other embodiments’, ‘alternative embodiment’, and thelike are intended to mean that any such features are included in one ormore embodiments of the present disclosure, but may or may notnecessarily be combined in the same embodiments.

As used herein, unless expressly stated to the contrary, use of thephrase ‘at least one of’, ‘one or more of’ and ‘and/or’ are open endedexpressions that are both conjunctive and disjunctive in operation forany combination of named elements, conditions, or activities. Forexample, each of the expressions ‘at least one of X, Y and Z’, ‘at leastone of X, Y or Z’, ‘one or more of X, Y and Z’, ‘one or more of X, Y orZ’ and ‘A, B and/or C’ can mean any of the following: 1) X, but not Yand not Z; 2) Y, but not X and not Z; 3) Z, but not X and not Y; 4) Xand Y, but not Z; 5) X and Z, but not Y; 6) Y and Z, but not X; or 7) X,Y, and Z. Additionally, unless expressly stated to the contrary, theterms ‘first’, ‘second’, ‘third’, etc., are intended to distinguish theparticular nouns (e.g., element, condition, module, activity, operation,etc.) they modify. Unless expressly stated to the contrary, the use ofthese terms is not intended to indicate any type of order, rank,importance, temporal sequence, or hierarchy of the modified noun. Forexample, ‘first X’ and ‘second X’ are intended to designate two Xelements that are not necessarily limited by any order, rank,importance, temporal sequence, or hierarchy of the two elements. Asreferred to herein, ‘at least one of’, ‘one or more of’, and the likecan be represented using the ‘(s)’ nomenclature (e.g., one or moreelement(s)).

In order to assist the United States Patent and Trademark Office (USPTO)and, additionally, any readers of any patent issued on this applicationin interpreting the claims appended hereto, Applicant wishes to notethat the Applicant: (a) does not intend any of the appended claims toinvoke paragraph (f) of 35 U.S.C. Section 112 as it exists on the dateof the filing hereof unless the words “means for” or “step for” arespecifically used in the particular claims; and (b) does not intend, byany statement in the specification, to limit this disclosure in any waythat is not otherwise reflected in the appended claims.

What is claimed is:
 1. A bearing system comprising: an inner bearingassembly comprising a spherical bearing and an outer race; an outerbearing assembly comprising a plurality of cylindrical roller bearings,an inner race, and an outer race; a race element comprising an innersurface and an outer surface, wherein the outer surface of the raceelement is the inner race for the outer bearing assembly and the innersurface of the race element is associated with the outer race for theinner bearing assembly; and inner securing elements associated with theinner surface of the race element that secure the outer race of theinner bearing assembly to the spherical bearing.
 2. The bearing systemof claim 1, wherein the inner bearing assembly allows tilting movementsof the bearing system.
 3. The bearing system of claim 1, wherein theouter bearing assembly allows rotational movements and wherein the outerbearing assembly supports, at least in part, radial loads for thebearing system.
 4. The bearing system of claim 1, wherein the outer raceof the inner bearing assembly is integral with the race element.
 5. Thebearing system of claim 1, wherein the outer race for the outer bearingassembly is rim material of a gear.
 6. The bearing system of claim 1,wherein the race element further comprises: an outer shoulder associatedwith the outer surface of the race element that maintains alignment ofthe plurality of cylindrical roller bearings with the inner race of theouter bearing assembly; and an outer structural element associated withthe outer surface of the race element that is to receive a retainingdevice.
 7. The bearing system of claim 6, wherein the retaining devicesecures the plurality of cylindrical roller bearings to the inner raceof the outer bearing assembly and wherein the inner race of the outerbearing assembly provides a clearance distance that allows axialmovements of the plurality of cylindrical roller bearings along theinner race.
 8. The bearing system of claim 1, wherein the sphericalbearing comprises an inner diameter to facilitate mounting the bearingsystem on a post.
 9. A bearing system comprising: an inner bearingassembly comprising a spherical bearing and an outer race; an outerbearing assembly comprising a plurality of cylindrical roller bearings,an inner race, and an outer race; a race element comprising an innersurface and an outer surface, wherein the outer surface of the raceelement is the inner race for the outer bearing assembly and the innersurface of the race element is associated with the outer race for theinner bearing assembly; and an outer shoulder associated with the outersurface of the race element that maintains alignment of the plurality ofcylindrical roller bearings with the inner race of the outer bearingassembly.
 10. The bearing system of claim 9, wherein the inner bearingassembly allows tilting movements of the bearing system.
 11. The bearingsystem of claim 9, wherein the outer bearing assembly allows rotationalmovements and wherein the outer bearing assembly supports, at least inpart, radial loads for the bearing system.
 12. The bearing system ofclaim 9, wherein the race element further comprises: inner securingelements associated with the inner surface of the race element thatsecure the outer race of the inner bearing assembly to the sphericalbearing; and an outer structural element associated with the outersurface of the race element that is to receive a retaining device. 13.The bearing system of claim 12, wherein the retaining device secures theplurality of cylindrical roller bearings to the inner race of the outerbearing assembly and wherein the inner race of the outer bearingassembly provides a clearance distance that allows axial movements ofthe plurality of cylindrical roller bearings along the inner race.
 14. Abearing system comprising: an inner bearing assembly comprising aspherical bearing and an outer race; an outer bearing assemblycomprising a plurality of cylindrical roller bearings, an inner race,and an outer race; a race element comprising an inner surface and anouter surface, wherein the outer surface of the race element is theinner race for the outer bearing assembly and the inner surface of therace element is associated with the outer race for the inner bearingassembly; and an outer structural element associated with the outersurface of the race element that is to receive a retaining device. 15.The bearing system of claim 14, wherein the inner bearing assemblyallows tilting movements of the bearing system.
 16. The bearing systemof claim 14, wherein the outer bearing assembly allows rotationalmovements and wherein the outer bearing assembly supports, at least inpart, radial loads for the bearing system.
 17. The bearing system ofclaim 14, wherein the race element further comprises: inner securingelements associated with the inner surface of the race element thatsecure the outer race of the inner bearing assembly to the sphericalbearing; and an outer shoulder associated with the outer surface of therace element that maintains alignment of the plurality of cylindricalroller bearings with the inner race of the outer bearing assembly. 18.The bearing system of claim 17, wherein the retaining device secures theplurality of cylindrical roller bearings to the inner race of the outerbearing assembly and wherein the inner race of the outer bearingassembly provides a clearance distance that allows axial movements ofthe plurality of cylindrical roller bearings along the inner race.